GP fees for children have been scrapped after the States backed the move last year.
Starting today, those under 18 can have free face-to-face and telephone appointments with their GP, nurses, paramedics and pharmacists.
Tests, such as blood samples, ECGs and pregnancy tests, are also covered under the scheme.
The Primary Care Body represents the island's practices and says it is delighted to support the project.
"General Practice continues to be the cornerstone of health services both locally and further afield.
"This joint commitment ensures that we can continue to provide high-quality family medicine whilst removing barriers."